Medically Reviewed by Carol DerSarkissian, MD on February 22, 2023
Contagious or Not?
1/11

Contagious or Not?

Some germs are contagious. That means they spread from person to person. But there are many types of infections you won’t get from another person. You might pick up germs by touching surfaces, or by eating or drinking things that have bacteria or viruses in them. Some diseases spread only through infected insects or other animals. Sometimes, microbes that live in or on your body can start to grow out of control and cause an infection.

Legionnaires Disease
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Legionnaires Disease

It’s a type of pneumonia that you get when you breathe in droplets of water or accidentally inhale water that has Legionella bacteria. Legionella live in lakes and streams. But people can become infected if the bacteria make their way into water systems and start to grow there, such as in shower heads, sink faucets, hot tubs, water heaters, or pipes.

Ear Infections
3/11

Ear Infections

They usually happen when an illness or allergies cause congestion in your nose, throat, and Eustachian tubes, which run from each ear to the back of the throat. The fluid that builds up in your middle ear allows germs to grow. While contagious cold and flu bugs sometimes lead to an ear infection, you can’t catch one from someone else.

Urinary Tract Infection
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Urinary Tract Infection

A UTI starts when bacteria from the rectum or somewhere else on the skin get into the urinary tract through the urethra. Women get UTIs more often than men mainly because their urethra is closer to the rectum. Some people get these infections after sex, when bacteria from a partner make their way into the urethra. You can help prevent this by peeing right after sex. But you don’t have to have sex to get this type of infection.

Sinus Infection (Sinusitis)
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Sinus Infection (Sinusitis)

Like an ear infection, sinus infections happen when mucus builds up in your sinuses and germs start to grow there. The common cold, which is a viral infection, is most often the cause of sinus infections. Sometimes, a bacterial infection is behind sinusitis.  If a virus is the cause, the infection is contagious. But, it’s more likely you’ll spread the cold than the sinus infection itself

Salmonella
6/11

Salmonella

This type of bacteria can cause an infection in your intestines. If you eat raw or undercooked food containing salmonella bacteria -- often meat, eggs, or poultry -- you can get a salmonella infection. Salmonella can end up on countertops and kitchen gadgets and then contaminate other food. Thorough cooking kills this bacteria. Symptoms of salmonella infection can include nausea, vomiting, diarrhea, cramps, fever, chills, and headache. Most people get Salmonella from eating food that has been contaminated, but it is possible to get it from the unwashed hands of the person preparing your food. “

Naegleria fowleri
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Naegleria fowleri

You might have heard it called a brain-eating amoeba. Naegleria fowleri causes a rare deadly brain infection. This tiny organism, or amoeba, gets into your brain through your nose. It lives in warm lakes or rivers,  or naturally hot water. Swimming pools without enough chlorine can host them too. The infection, which causes seizures, confusion, and hallucination, can kill people in as little as 5 days.

Rabies
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Rabies

You get rabies when an animal that carries the virus  bites you. Most cases involve infected bats, coyotes, dogs, and cats. Rabies is deadly, but it’s rare for people to get it. If you are bit or scratched by an animal that might have rabies, a doctor can give you a vaccine to protect you from the virus.

Infections From Ticks
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Infections From Ticks

Ticks can pass many different bacteria and viruses to people through a bite. Some bacterial infections that ticks carry include Lyme disease and Rocky Mountain spotted fever. Some well-known viruses are Colorado tick fever and Bourbon virus. If a tick burrows into your skin, remove it with tweezers, not a lit match. If possible, seal the tick in a container and freeze it. If you get sick in the next couple of weeks see a doctor. If possible, bring the tick. 

Infections From Mosquitoes
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Infections From Mosquitoes

Mosquitoes carrying viruses, including malaria, Zika, West Nile, yellow fever, dengue fever, and chikungunya, can pass them to people through a bite. These infections tend to happen in specific parts of the world. 

Infections From Rodents
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Infections From Rodents

These usually happen when people are in contact with waste from infected rats, mice, or other rodents. You can also breathe dust that’s carrying specks of rodent droppings or urine. You can get hantavirus, hemorrhagic fever, and other illnesses. If you need to clean up droppings, don’t stir up dust with a broom or vacuum cleaner. Put on gloves, spray the area with disinfectant, and wipe it clean. Then take care of the rodent that left the droppings.